Sublingual immunotherapy (SLIT) with reduced oral itchiness is disclosed. The improved sublingual immunotherapy combines a monotonically increasing dose of allergen, along with a constant dose of mast cell stabilizer, thereby substantially avoiding the oral itchiness and other uncomfortable adverse reactions typically experienced with SLIT, which can improve patient compliance. An antihistamine and/or a leukotriene inhibitor can also be added along with the mast cell stabilizer. Multi-layer and/or coated tablets, and flexible paired ampoules with special features to advantageously time the dose of the allergen relative to the dose of the mast cell stabilizer, have been provided to effectively administer the improved sublingual immunotherapy in a highly convenient manner. Methods, preparations, and apparatuses for administration of SLIT, apparatus for sequentially dispensing, methods for producing a sequence of allergen doses with reduced adverse reactions, methods for producing a stock solution for dilution, and methods for producing cooperative pre-filled vials are also disclosed.